To reduce the US dependence on crude oil and limit the environmental impact of fossil fuels usage, ambitious long term goals have been set to displace a significant portion of the US transportation fuel demand with biofuels in the next couple of decades. Thermochemical conversion of biomass appears as a promising route for biofuel production that uses heat to initially convert the biomass into either a gas, primarily composed of carbon monoxide and hydrogen ("gasification"), or a liquid bio-oil bearing some resemblance to crude oil (pyrolysis). These intermediate products can then be further processed and refined to obtain fungible transportation fuels. Existing technologies need to overcome significant technical barriers to become environmentally and economically viable. These barriers include the inability to handle diverse biomass feedstock in a consistent manner, poor characterization and control of the intermediate conversion compounds, undesirable product formation, or the lack of reliable scale-up rules to design efficient commercial plants. Our research group aims at gaining a more fundamental understanding of the chemical and physical processes involved in biomass thermochemical conversion through the development of an array of numerical tools and models suitable for use in Computational Fluid Dynamics (CFD). This presentation will focus on biomass conversion chemistry, as an accurate description of the chemical kinetics is key to achieve predictive CFD simulations. First, a semi-detailed reaction mechanism assembled and validated based on the current state of understanding of the biomass kinetics will be described. Since the level of detail involved in such a scheme prohibits its direct use in CFD, reduced-order models, which only contain the minimum amount of information needed to accurately reproduce the behavior of the full chemical description, are developed using automatic techniques. These compact schemes can then be used in large-scale simulations of biomass conversion reactors, providing valuable insights on how the chemical processes can be impacted by the dynamics of the multiphase flow inside the reactor.

Biography:

Dr. Pepiot is interested in the production and utilization of renewable liquid transportation fuels from a modeling perspective. Her current work aims at gaining a better understanding of the biomass thermochemical conversion processes such as pyrolysis and gasification through the use of detailed multi-scale numerical techniques. Dr. Pepiot is also interested in the development of automatic tools to reduce the complexity of large chemical mechanisms and generate low-order kinetic models for conventional and bio-fuels combustion. Prior to joining the Cornell faculty in 2011, Dr. Pepiot was a research scientist at the National Renewable Energy Laboratory in Golden, Colorado, developing chemical and multi-phase flow models to investigate biomass gasification in fluidized bed reactors for ethanol production. Dr. Pepiot has a Ph.D. and M.S. in Mechanical Engineering from Stanford University, and a M.S. in Aeronautics and Astronautics from the Ecole Nationale Superieure de l'Aeronautique et de l'Espace (Supaero) in Toulouse, France.